This invention relates to slot array radar antennas of the type typically formed in an antenna pod and adapted for being carried by an aircraft. More particularly, this invention relates to a slot array antenna where the slots have a novel configuration and in which the antenna pod structure is comparatively small as compared to the prior art for the frequencies involved. The slots of the present invention are physical interruptions or cuts in an otherwise continuous ground plane and the slots form the elements of a radar antenna. The prior art also refers to certain surfacemounted or stripline slot antennas as simply "slot" antennas and these are totally different from applicant's invention.
Applicant is aware of U.S. Pat. No. 3,074,063 which shows a circumferential slot array radar antenna on a cylindrical cavity and designed to radiate uniformly in a radial direction. Applicant's invention is a steerable antenna having a particular shaped slot array and is different from the patent.
U.S. Pat. No. 3,293,645 and U.S. Pat. No. 3,518,685 also show slot array radar antennas but do not anticipate applicant's invention.
U.S. Pat. No. 2,573,461 shows a slot array antenna backed by a cavity in a cylindrical environment and in which the antenna is steerable. However, the design of this antenna does not anticipate applicant's invention.
U.S. Pat. No. 3,623,162 shows a particular shaped slot array radar antenna, namely, a bow tie slot shape, adapted to the shape of an air foil edge such as a wing edge, however, and not to a cylinder. Finally, U.S. Pat. No. 4,063,246 shows another development in slot array radar antennas but which also does not anticipate applicant's invention.
Generally, slot radar antenna pods are well-known in the art and the advancement of the present invention relates to the shape and configuration of particular slots on a cylindrical surface. It can be shown theoretically that a slot antenna is the current source analog to a dipole antenna driven by a voltage source.